The invention relates generally to medical technology, and more particularly, it relates to injection therapy. Devices, which drive injection cannula into the body by first sucking the skin into the cannula tip are known from prior art. With the suction injection, only the upper layers of the skin are penetrated by the cannula tip, and the greater vessels, nerves and bone are not reached, which avoids pain and dangerous injection into blood vessels. The finest vessels in fatty tissue can be penetrated by the cannula tip. These vessels can be hurt by liquid pressure. In particular, the injection of christalline heparine, insulin or allergene can trigger dangerous conditions of shock. There are even injectors on the market, which permit the patient to alter the depth, which the needle, driven by spring pressure, will penetrate the tissue before the contents of the syringe are emptied under considerable pressure, although the patient himself cannot be the proper judge of this. The usual suction movement of the syringe piston to the end of the cannula within the container does not in this case take place. In one of these injectors, a transparent water-like cold-sterilizer is used for the constant cleansing of the dose pump within the injector. This fluid can easily be mistaken for insulin. Only the fact, that it is difficult and unpleasant to use, has prevented fatalities up til now. If suction injection makes the suction movement of a syringe unnecessary, this raises the question, why, in view of the possibility of dosing from large supply bottles, research on injectors which use disposable syringes is of use. It is useful, in particular, because, especially in doctors' practices and clinics, there is always danger of contagion, particularly of hepatitis, even if there is only a brief and limited contact to the medicine supply, and because there will be interruptions in use.
The only suction injector for use on humans, which is known to the inventor, is not suitable for one-handed use, because negative pressure is caused by the movement of the piston. It was never put on the market for that reason, because the extent of the body surface, which can be used for injection, and the careful treatment of tissue are among the most important priorities for the invention.